The present invention relates to methods and devices for performing medical procedures, including, but not limited to, gynecologic, otologic, neurosurigical, and gastrointestinal procedures, and move particularly to medical devices such as a speculum, having a built-in capability for permitting ultrasound visualization of a procedural site.
There are a number of gynecological procedures for which it would be advantageous to have the capability of direct transvaginal ultrasound visualization, for the purpose of permitting the medical practitioner to guide catheters and other instruments into the cervical canal and uterine cavity. For example, with the common infertility treatment known as In Vitro Fertilization (IVF), the crucial last step is the transfer of the fertilized eggs (embryos) through the cervix into the uterine cavity. This step is identified in the practice as transcervical embryo transfer. Embryos are usually transferred by first placing a speculum into the vagina to visualize the cervix. Then, a catheter containing the embryos at its tip is threaded through the cervix into the uterine cavity. The embryos are then released. Embryo transfers are thus commonly performed by feel. The catheter tip is felt to thread its way through the cervix into the uterine cavity.
Ultrasound visualization of the catheter as it traverses the cervix into the uterine cavity would provide many advantages. Ultrasound visualization would facilitate catheter negotiation of a difficult tortuous cervical canal, for example, and would allow more precise placement of the catheter tip within the uterine cavity. There are clinical studies which argue that more precise placement of the embryos in the uterine cavity improves pregnancy rates. Clinical studies also indicate that, using current techniques, some embryos may be inadvertently placed within the cervical canal. Ultrasound visualization would help to ensure the release of embryos into the uterine cavity. Embryos themselves are too small to visualize, but they can be placed adjacent to two small air bubbles in the catheter, subsequent to which the air bubbles can easily be detected by ultrasound imaging techniques.
In the current state of the art, ultrasound visualization of the cervix and uterus can be accomplished in three ways. One way is to place an ultrasound probe, of known construction, on the abdomen of the patient. This transabdominal approach makes it very difficult to adequately visualize the cervical canal and uterine cavity. This problem is worsened in the case of obesity, deep retroverted and retroflexed positions of the uterus, suboptimally positioned uteri, and intervention of the bowel between the skin and the uterus. The pubic bone can also obstruct visualization. The transabdominal approach usually requires a full, uncomfortable bladder for optimal visualization of the cervical canal and uterine cavity. The transabdominal approach also requires two people, one to hold the abdominal ultrasound probe in the best orientation for cervical canal and uterine cavity visualization, and the other to do the actual transfer, which includes threading the catheter through the cervical canal and into the uterine cavity, as well as releasing the embryos. Thus, the sonographic image of the cervical canal and the uterine cavity obtained by the transabdominal probe is more uncomfortable and usually inferior in quality to that obtained by use of the transvaginal probe. Nonetheless, transabdominal ultrasound is the visualization method most often employed with embryo transfers because it does not interfere with the normal procedure of embryo transfer.
The second visualization approach which is currently employed is transvaginal ultrasound. This approach provides an improved visualization of the cervical canal and uterine cavity relative to transabdominal ultrasound, but interferes with the most common embryo transfer techniques by virtue of the ultrasonic probe being physically present in the vagina. Suboptimal ways around this problem include:
1) Placing the speculum in the vagina first. Then, the catheter is threaded through the cervix and into the uterine cavity by feel. While holding the catheter in position, the speculum is removed. The transvaginal probe is then placed into the vagina while still holding the catheter in place, while hoping that the probe's placement will not disturb the catheter's placement unduly.
2) Placing the speculum in the vagina first. Then, the catheter is threaded through the cervix and into the uterine cavity by feel. While holding the catheter, and with the speculum still in place, an assistant places the transvaginal probe into the vagina. This awkward method thus requires two people, one to hold the transvaginal probe in position to obtain visualization of the cervical canal and uterine cavity, and the second to hold the catheter, and then, while the catheter tip is in the optimum position, to depress the syringe attached to the catheter and thus release the embryos.
3) Placing the speculum in the vagina first. Then, the transvaginal probe is placed through the speculum into the vagina. Finally, an attempt is made to thread the catheter through the external cervical os into the uterine cavity while the transvaginal probe is also within the speculum. This approach is very difficult because the probe within the speculum physically and visually blocks access to the external cervical os.
As is obvious from the above descriptions, each of these described suboptimal approaches creates difficulty and unnecessary complications, thereby reducing the opportunity for a successful outcome.
Yet a third visualization approach sometimes employed in certain procedures is transrectal ultrasound, but this technique for visualization is cumbersome, compromising, and uncomfortable.
What is needed, therefore, is a visualization approach which allows the best of both worlds; i.e. superior transvaginal ultrasonographic imaging without interfering with typical medical procedures, such as transcervical embryo transfer, hysteroscopic procedures, and the like.